Bio-impedance of breast tumors has been a source for numerous scientific research studies since discovery of electricity by Volta in 1800. It was the Cole brothers (in 1930) who mathematically and physically described dielectric properties. Cole-Cole equations are used in bio-impedance analysis. Since the late 1960's, bio-impedance analysis has benefited from the advent of microprocessors and digital signal processing.
The method can also be used to characterize biological tissue electrical properties in many different applications including blood analysis, body muscle and fat content as well as in estimating the length of the root canal in teeth see U.S. Pat. No. 6,425,875 “Method and device for detection of tooth root apex.”
Electrical Impedance Scanning (EIS) has been described in literature [1] [2] and machines have been built to be used on patients. The EIS of the breast relies on body transmission of alternating electricity using an electrical patch attached to the arm and a hand-held cylinder. The electrical signal flows through the breast where it is then measured at skin level by a probe placed on the breast. Examples of such devices are the T Scan 2000 from Mirabel Medical Systems, which has been cleared by the FDA for adjunctive diagnosis in conjunction with mammography, and the follow-on T Scan 2000 ED. Mirabel devices are covered under multiple patents among which are Andrew L. Pearlman (U.S. Pat. No. 7,141,019), Ron Ginor (U.S. Pat. No. 7,302,292) and Ginor and Nachaliel (U.S. Patent Application Pub. No. 2007/0293783). Other devices are the one from Biofield Corp. (Cuzick et al, U.S. Pat. No. 6,351,666), and the device of Richard J. Davies (U.S. Pat. Nos. 6,922,586 and 7,630,759).
The benefits of having a non-mammographic mechanism to screen for patients whose age is less that age 50 are significant. Below age of 40, radiation from use of screening mammography will cause more cancer than it saves. Between 40 and 50 there is a break even where one saves approximately as many of cancers caused. Above 50 years of age mammography works well because a tumor contrasts well against normal breast tissue. Below age 40 the density of the breast tissue is so high that it difficult to impossible to differentiate from a tumor. The same is not quite as true for women in the age group of 40 to 50 but the problem with mammographic differentiation between normal breast tissue and cancer remains.
Asymptomatic young women under the age of 40 are not routinely screened (in the United States) but instead depending on breast self-examination (BSE) and clinical breast examination (CBE). Carcinoma of the breast is generally more aggressive in younger women. The availability of a diagnostic test that does not involve radiation would be of significant benefit.
Mammograms only demonstrate presence of calcium and not all DCIS masses have calcium deposits. MRI and PET only detect increases in vascularity that may or may not be present. One consideration in mammography is that the results are not necessarily stable; some 30% of “cancer” detected on mammography disappears.
Another factor is the detection of breast cancer and other abnormalities are the costs of doing procedures. It would of significant benefit, particularly in developing countries, to have a low cost procedure. Of course, lower cost and resulting wider availability is important in developed nations as well.
Desirability of the detection, location, of tissue masses and other abnormalities is not restricted to the breast alone. It would be highly desirable to non-invasively or minimally invasively to apply impedance to techniques to other tissues such as those of the prostate, lung, liver, oral cavity, vaginal cavity, rectum, colon, and other organs or body locations as well as to apply those techniques to tissue biopsy specimens from any part of a living or formerly living creature.